Technical Abstract:
In several described sources of genetic resistance to root-knot nematode (RKN), Meloidogyne incognita including ‘Acala NemX’ and Auburn 623, interaction of at least two genes and transgressive segregation occur, and resistance to RKN in cotton may involve the interaction of several genes. The concentration of RKN resistance factors on chromosome 11 indicates that much can be gained by fine mapping this genomic region. With the support of Cotton Inc., Cary, NC, two BAC libraries are being developed from two different germplasm resistance sources, N901 (NemX origin) and M120 (Auburn 623 origin). Previously identified diagnostic DNA markers (RFLP, BNL, CIR, MUSS, MUCS, MUSB, NAU, etc.) will be used directly for map-based cloning of a gene(s) or QTL from mapped marker to a locus closely linked to the gene or QTL of interest. The new genome BAC resource will allow us to fine map RKN resistance region(s) on chromosome 11 and to obtain DNA sequence information for marker development and gene discovery. While progress in cotton genomics may be lagging behind that in other agronomic crops, the past decade has seen substantial growth and development, conceptually and technically. Our ultimate objective is to accelerate the incorporation of RKN resistance in commercial cultivars by increasing knowledge about the inheritance of RKN resistance genes, developing markers for marker-assisted selection (MAS), and increasing knowledge of the structure of the cotton genome.